Fisker knows he’ll need more than a big-ticket sedan to make his company more than a niche player. He’s already working on a convertible called the Karma S that we’ll see in 2011, but says the company’s breakthrough will come when it unveils a midsize sedan. That car, he said, will sell for $39,900 after the $7,500 federal tax credit for EVs, and could be on the road by 2012.